The present invention relates to apparatus for moving toll bars or barriers between blocking and retracted positions, especially for moving toll bars between horizontal and vertical end positions. Such bars are utilized at toll gates, for example, on parkways or other toll roads, at the entrances to or exits from parking areas, at entrances to parkways or expressways and for analogous purposes. More particularly, the invention relates to improvements in apparatus for moving toll bars or analogous barriers between their end positions by resorting to a prime mover.
Presently known apparatus for moving toll bars normally comprise a motor which transmits motion to the toll bar by way of a combined worm and crank drive which is self-locking in each and every angular position of the bar. The self-locking action is furnished by the worm drive. Such self-locking action is desirable in one or both end positions of the bar, i.e., when the bar extends horizontally across a lane in which vehicles are driven, for instance, into or from a parking area and preferably also when the bar is held in vertical or nearly vertical position to allow the vehicles to pass. Self-locking action in vertical position of the bar is desirable when the apparatus is idle to prevent accidental descent to the horizontal position. Self-locking action in the horizontal position of the bar is desirable to prevent unauthorized lifting of the bar, e.g., by a driver who wishes to drive his or her vehicle into or from a parking area without paying the prescribed amount of money. On the other hand, self-locking action in an intermediate position of the bar is not desirable, especially if the toll booth is unattended which is customary at toll gates that can be passed by drivers having the exact change. For example, if the bar accidentally engages the trunk, roof or hood of a slowly moving vehicle, the driver of the vehicle, another occupant or an attendant should be in a position to lift the bar with a minimum of effort. In many presently known apparatus, the motor which is coupled to the input element of transmission for the bar is automatically disconnected when the bar encounters an obstruction during movement to the one or the other end position. A conventional apparatus then locks the bar in the intermediate position and the driver is unable to immediately lift the bar without the exertion of a substantial effort and/or without damaging certain parts of the apparatus.